Wide ratio transmissions with three interconnected planetary gear sets

ABSTRACT

The family of transmissions has a plurality of members that can be utilized in powertrains to provide at least eight forward speed ratios and one reverse speed ratio. The transmission family members include three planetary gear sets having seven torque-transmitting mechanisms and three fixed interconnections. The powertrain includes an engine and torque converter that is continuously connected to at least one of the planetary gear members and an output member that is continuously connected with another one of the planetary gear members. The seven torque-transmitting mechanisms provide interconnections between various gear members, the input shaft, the output shaft, and the transmission housing, and are operated in combinations of two to establish at least eight forward speed ratios and at least one reverse speed ratio.

TECHNICAL FIELD

The present invention relates to a family of power transmissions havingthree planetary gear sets that are controlled by seventorque-transmitting devices to provide at least eight forward speedratios and at least one reverse speed ratio.

BACKGROUND OF THE INVENTION

Passenger vehicles include a powertrain that is comprised of an engine,multi-speed transmission, and a differential or final drive. Themulti-speed transmission increases the overall operating range of thevehicle by permitting the engine to operate through its torque range anumber of times. The number of forward speed ratios that are availablein the transmission determines the number of times the engine torquerange is repeated. Early automatic transmissions had two speed ranges.This severely limited the overall speed range of the vehicle andtherefore required a relatively large engine that could produce a widespeed and torque range. This resulted in the engine operating at aspecific fuel consumption point during cruising, other than the mostefficient point. Therefore, manually-shifted (countershafttransmissions) were the most popular.

With the advent of three- and four-speed automatic transmissions, theautomatic shifting (planetary gear) transmission increased in popularitywith the motoring public. These transmissions improved the operatingperformance and fuel economy of the vehicle. The increased number ofspeed ratios reduces the step size between ratios and therefore improvesthe shift quality of the transmission by making the ratio interchangessubstantially imperceptible to the operator under normal vehicleacceleration.

It has been suggested that the number of forward speed ratios beincreased to six or more. Six-speed transmissions are disclosed in U.S.Pat. No. 4,070,927 issued to Polak on Jan. 31, 1978; U.S. Pat. No.6,071,208 issued to Koivunen on Jun. 6, 2000; U.S. Pat. No. 5,106,352issued to Lepelletier on Apr. 21, 1992; U.S. Pat. No. 5,599,251 issuedto Beim and McCarrick on Feb. 4, 1997; and U.S. Pat. No. 6,422,969issued to Raghavan and Usoro on Jul. 23, 2002.

Six-speed transmissions offer several advantages over four- andfive-speed transmissions, including improved vehicle acceleration andimproved fuel economy. While many trucks employ power transmissionshaving six or more forward speed ratios, passenger cars are stillmanufactured with three- and four-speed automatic transmissions andrelatively few five or six-speed devices due to the size and complexityof these transmissions.

Seven-speed transmissions are disclosed in U.S. Pat. No. 4,709,594 toMaeda; U.S. Pat. No. 6,053,839 to Baldwin et al.; and U.S. Pat. No.6,083,135 to Baldwin et al.; U.S. Pat. No. 6,623,397 issued to Raghavan,Bucknor and Usoro. Eight speed transmissions are disclosed in U.S. Pat.No. 6,375,592 issued to Takahashi et al.; U.S. Pat. No. 6,425,841 issuedto Haka; U.S. Pat. No. 6,471,615 issued to Naraki et al.; and U.S. Pat.No. 6,558,287 issued to Hayabuchi et al. The Haka and Hayabuchitransmissions utilize three planetary gear sets and six torquetransmitting devices, including two brakes and two clutches, to provideeight forward speed ratios and a reverse speed ratio. One of theplanetary gear sets is positioned and operated to establish two fixedspeed input members for the remaining two planetary gear sets. The Hakatransmission requires two double-transition shifts and the Hayabuchitransmission offers low overall ratio spread for an eight speedtransmission. The Takahashi and Naraki transmissions employ a complexarrangement of multiple planetary gear sets, multiple countershaft gearsets and multiple torque transmitting devices (clutches, brakes andfreewheelers) to provide eight forward speed ratios and a reverse speedratio. Seven-, eight- and nine-speed transmissions provide furtherimprovements in acceleration and fuel economy over six-speedtransmissions. However, like the six-speed transmissions discussedabove, the development of seven-, eight- and nine-speed transmissionshas been precluded because of complexity, size and cost.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved familyof transmissions having three planetary gear sets controlled to provideat least eight forward speed ratios and at least one reverse speedratio.

In one aspect of the present invention, the family of transmissions hasthree planetary gear sets, each of which includes a first, second andthird member, which members may comprise a sun gear, a ring gear, or aplanet carrier assembly member.

In referring to the first, second and third gear sets in thisdescription and in the claims, these sets may be counted “first” to“third” in any order in the drawings (i.e., left to right, right toleft, etc.). Additionally, the first, second or third members of eachgear set may be counted “first” to “third” in any order in the drawings(i.e., top to bottom, bottom to top, etc.) for each gear set.

In another aspect of the present invention, planet carrier assemblymembers of each of the planetary gear sets may be single pinion-carriersor double pinion-carriers.

In yet another aspect of the present invention, a first member of thefirst planetary gear set is continuously interconnected to a firstmember of the second planetary gear set through a first interconnectingmember.

In yet another aspect of the present invention, a second member of thefirst planetary gear set is continuously interconnected to a firstmember of the third planetary gear set through a second interconnectingmember.

In yet another aspect of the present invention, a second member of thesecond planetary gear set is continuously interconnected to a secondmember of the third planetary gear set through a third interconnectingmember.

In yet a further aspect of the invention, each family memberincorporates an input shaft which is continuously connected with amember of the planetary gear sets and an output shaft which iscontinuously connected with another member of the planetary gear sets.

In still a further aspect of the invention, a first torque-transmittingmechanism, such as a brake, selectively interconnects a member of thefirst or second planetary gear set with a stationary member(transmission housing).

In another aspect of the invention, a second torque-transmittingmechanism, such as a brake, selectively interconnects a member of thesecond or third planetary gear set with the stationary member(transmission housing).

In a still further aspect of the invention, a third torque-transmittingmechanism, such as a brake, selectively interconnects a member of thesecond or third planetary gear set with the stationary member(transmission housing).

In a still further aspect of the invention, a fourth torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst planetary gear set with a member of the second or third planetarygear set.

In a still further aspect of the invention, a fifth torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thesecond planetary gear set with a member of the first or third planetarygear set.

In still another aspect of the invention, a sixth torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst, second or third planetary gear set with another member of thefirst, second or third planetary gear set.

In still another aspect of the invention, a seventh torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst, second or third planetary gear set with another member of thefirst, second or third planetary gear set. Alternatively, the seventhtorque-transmitting mechanism, such as a brake, selectivelyinterconnects a member of the first, second or third planetary gear setwith the stationary member (transmission housing).

In still another aspect of the invention, the seven torque-transmittingmechanisms are selectively engageable in combinations of two to yield atleast eight forward speed ratios and at least one reverse speed ratio.

The resulting transmission provides a significantly wider ratio spreadin comparison to transmissions with fewer speed ratios.

The above features and other features and advantages of the presentinvention are readily apparent from the following detailed descriptionof the best modes for carrying out the invention when taken inconnection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a schematic representation of a powertrain including aplanetary transmission incorporating a family member of the presentinvention;

FIG. 1 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 1 a;

FIG. 2 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 2 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 2 a;

FIG. 3 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 3 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 3 a;

FIG. 4 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 4 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 4 a;

FIG. 5 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 5 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 5 a;

FIG. 6 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 6 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 6 a;

FIG. 7 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 7 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 7 a;

FIG. 8 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 8 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 8 a;

FIG. 9 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 9 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 9 a;

FIG. 10 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 10 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 10 a;

FIG. 11 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention; and

FIG. 11 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 11 a.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, wherein like characters represent the same orcorresponding parts throughout the several views, there is shown in FIG.1 a a powertrain 10 having a conventional engine and torque converter12, a planetary transmission 14, and a conventional final drivemechanism 16.

The planetary transmission 14 includes an input shaft 17 continuouslyconnected with the engine and torque converter 12, a planetary geararrangement 18, and an output shaft 19 continuously connected with thefinal drive mechanism 16. The planetary gear arrangement 18 includesthree planetary gear sets 20, 30 and 40.

The planetary gear set 20 includes a sun gear member 22, a ring gearmember 24, and a planet carrier assembly 26. The planet carrier assembly26 includes a plurality of pinion gears 27 rotatably mounted on acarrier member 29 and disposed in meshing relationship with both the sungear member 22 and the ring gear member 24.

The planetary gear set 30 includes a sun gear member 32, a ring gearmember 34, and a planet carrier assembly member 36. The planet carrierassembly member 36 includes a plurality of pinion gears 37 rotatablymounted on a carrier member 39 and disposed in meshing relationship withboth the sun gear member 32 and the ring gear member 34.

The planetary gear set 40 includes a sun gear member 42, a ring gearmember 44, and a planet carrier assembly member 46. The planet carrierassembly member 46 includes a plurality of pinion gears 47 rotatablymounted on a carrier member 49 and disposed in meshing relationship withboth the sun gear member 42 and the ring gear member 44.

The planetary gear arrangement also includes seven torque-transmittingmechanisms 50, 52, 54, 56, 57, 58 and 59. The torque-transmittingmechanisms 50, 52, 54 and 56 are rotating-type torque-transmittingmechanisms, commonly termed clutches. The torque-transmitting mechanisms57, 58 and 59 are stationary-type torque-transmitting mechanisms,commonly termed brakes or reaction clutches.

The input shaft 17 is continuously connected with the sun gear member22, and the output shaft 19 is continuously connected with the ring gearmember 44. The sun gear member 22 is continuously connected with the sungear member 32 through the interconnecting member 70. The ring gearmember 24 is continuously connected with the sun gear member 42 throughthe interconnecting member 72. The planet carrier assembly member 36 iscontinuously connected with the planet carrier assembly member 46through the interconnecting member 74.

The ring gear member 24 is selectively connectable with the ring gearmember 34 through the clutch 50. The sun gear member 22 is selectivelyconnectable with the planet carrier assembly member 26 through theclutch 52. The sun gear member 22 is selectively connectable with theplanet carrier assembly member 36 through the clutch 54. The planetcarrier assembly member 26 is selectively connectable with the ring gearmember 34 through the clutch 56. The ring gear member 24 is selectivelyconnectable with the transmission housing 60 through the brake 57. Theplanet carrier assembly member 26 is selectively connectable with thetransmission housing 60 through the brake 58. The planet carrierassembly member 46 is selectively connectable with the transmissionhousing 60 through the brake 59.

As shown in FIG. 1 b, and in particular the truth table disclosedtherein, the torque-transmitting mechanisms are selectively engaged incombinations of two to provide eight forward speed ratios (as well as anextra third forward speed ratio (3′)) and two reverse speed ratios.

The reverse #2 speed ratio is established with the engagement of theclutch 50 and the brake 58. The clutch 50 connects the ring gear member24 with the ring gear member 34, and the brake 58 connects the planetcarrier assembly member 26 with the transmission housing 60. The sungear member 22 and the sun gear member 32 rotate at the same speed asthe input shaft 17. The planet carrier assembly member 26 does notrotate. The ring gear member 24 and the ring gear member 34 rotate atthe same speed as the sun gear member 42. The ring gear member 24rotates at a speed determined from the speed of the sun gear member 22and the ring gear/sun gear tooth ratio of the planetary gear set 20. Theplanet carrier assembly member 36 rotates at the same speed as theplanet carrier assembly member 46. The planet carrier assembly member 36rotates at a speed determined from the speed of the ring gear member 34,the speed of the sun gear member 32 and the ring gear/sun gear toothratio of the planetary gear set 30. The ring gear member 44 rotates atthe same speed as the output shaft 19. The ring gear member 44, andtherefore the output shaft 19, rotates at a speed determined from thespeed of the planet carrier assembly member 46, the speed of the sungear member 42 and the ring gear/sun gear tooth ratio of the planetarygear set 40. The numerical value of the reverse #2 speed ratio isdetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 20, 30 and 40.

The reverse #1 speed ratio is established with the engagement of theclutch 52 and the brake 59. The clutch 52 connects the planet carrierassembly member 26 with the sun gear member 22, and the brake 59connects the planet carrier assembly member 46 with the transmissionhousing 60. The planetary gear set 20 and the sun gear members 32, 42rotate at the same speed as the input shaft 17. The planet carrierassembly member 36 and the planet carrier assembly member 46 do notrotate. The ring gear member 44 rotates at the same speed as the outputshaft 19. The ring gear member 44, and therefore the output shaft 19,rotates at a speed determined from the speed of the sun gear member 42and the ring gear/sun gear tooth ratio of the planetary gear set 40. Thenumerical value of the reverse #1 speed ratio is determined utilizingthe ring gear/sun gear tooth ratio of the planetary gear set 40.

The first forward speed ratio is established with the engagement of theclutch 50 and the brake 59. The clutch 50 connects the ring gear member24 with the ring gear member 34, and the brake 59 connects the planetcarrier assembly member 46 with the transmission housing 60. The sungear member 22 and the sun gear member 32 rotate at the same speed asthe input shaft 17. The ring gear member 24 and the ring gear member 34rotate at the same speed as the sun gear member 42. The planet carrierassembly member 36 and the planet carrier assembly member 46 do notrotate. The ring gear member 34 rotates at a speed determined from thespeed of the sun gear member 32 and the ring gear/sun gear tooth ratioof the planetary gear set 30. The ring gear member 44 rotates at thesame speed as the output shaft 19. The ring gear member 44, andtherefore the output shaft 19, rotates at a speed determined from thespeed of the sun gear member 42 and the ring gear/sun gear tooth ratioof the planetary gear set 40. The numerical value of the first forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratiosof the planetary gear sets 30 and 40.

The second forward speed ratio is established with the engagement of thebrake 58 and the brake 59. The brake 58 connects the planet carrierassembly member 26 with the transmission housing 60, and the brake 59connects the planet carrier assembly member 46 with the transmissionhousing 60. The sun gear member 22 and the sun gear member 32 rotate atthe same speed as the input shaft 17. The ring gear member 24 rotates atthe same speed as the sun gear member 42. The planet carrier assemblymember 26 does not rotate. The speed of the ring gear member 24 isdetermined from the speed of the sun gear member 22 and the ringgear/sun gear tooth ratio of the planetary gear set 20. The planetcarrier assembly member 46 and the planet carrier assembly member 36 donot rotate. The ring gear member 44 rotates at the same speed as theoutput shaft 19. The ring gear member 44, and therefore the output shaft19, rotates at a speed determined from the speed of the sun gear member42 and the ring gear/sun gear tooth ratio of the planetary gear set 40.The numerical value of the second forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear sets20 and 40.

The extra third forward speed ratio (3′) is established with theengagement of the clutch 50 and the brake 57. The clutch 50 connects thering gear member 24 with the ring gear member 34, and the brake 57connects the ring gear member 24 with the transmission housing 60. Thesun gear member 22 and the sun gear member 32 rotate at the same speedas the input shaft 17. The ring gear member 24, the ring gear member 34and the sun gear member 42 do not rotate. The planet carrier assemblymember 36 rotates at the same speed as the planet carrier assemblymember 46. The speed of the planet carrier assembly member 36 isdetermined from the speed of the sun gear member 32 and the ringgear/sun gear tooth ratio of the planetary gear set 30. The ring gearmember 44 rotates at the same speed as the output shaft 19. The ringgear member 44, and therefore the output shaft 19, rotates at a speeddetermined from the speed of the planet carrier assembly member 46 andthe ring gear/sun gear tooth ratio of the planetary gear set 40. Thenumerical value of the extra third forward speed ratio (3′) isdetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 30 and 40.

The third forward speed ratio is established with the engagement of theclutch 56 and the brake 59. The clutch 56 connects the planet carrierassembly member 26 with the ring gear member 34, and the brake 59connects the planet carrier assembly member 46 with the transmissionhousing 60. The sun gear member 22 and the sun gear member 32 rotate atthe same speed as the input shaft 17. The planet carrier assembly member26 rotates at the same speed as the ring gear member 34. The ring gearmember 24 rotates at the same speed as the sun gear member 42. The ringgear member 24 rotates at a speed determined from the speed of theplanet carrier assembly member 26, the speed of the sun gear member 22and the ring gear/sun gear tooth ratio of the planetary gear set 20. Theplanet carrier assembly member 36 and the planet carrier assembly member46 do not rotate. The ring gear member 34 rotates at a speed determinedfrom the speed of the sun gear member 32 and the ring gear/sun geartooth ratio of the planetary gear set 30. The ring gear member 44rotates at the same speed as the output shaft 19. The ring gear member44, and therefore the output shaft 19, rotates at a speed determinedfrom the speed of the sun gear member 42 and the ring gear/sun geartooth ratio of the planetary gear set 40. The numerical value of thethird forward speed ratio is determined utilizing the ring gear/sun geartooth ratios of the planetary gear sets 20, 30 and 40.

The fourth forward speed ratio is established with the engagement of theclutch 56 and the brake 58. The clutch 56 connects the planet carrierassembly member 26 with the ring gear member 34, and the brake 58connects the planet carrier assembly member 26 with the transmissionhousing 60. The sun gear member 22 and the sun gear member 32 rotate atthe same speed as the input shaft 17. The ring gear member 24 rotates atthe same speed as the sun gear member 42. The planet carrier assemblymember 26 and the ring gear member 34 do not rotate. The speed of thering gear member 24 is determined from the speed of the sun gear member22 and the ring gear/sun gear tooth ratio of the planetary gear set 20.The planet carrier assembly member 36 rotates at the same speed as theplanet carrier assembly member 46. The speed of the planet carrierassembly member 36 is determined from the speed of the sun gear member32 and the ring gear/sun gear tooth ratio of the planetary gear set 30.The ring gear member 44 rotates at the same speed as the output shaft19. The ring gear member 44, and therefore the output shaft 19, rotatesat a speed determined from the speed of the planet carrier assemblymember 46, the speed of the sun gear member 42 and the ring gear/sungear tooth ratio of the planetary gear set 40. The numerical value ofthe fourth forward speed ratio is determined utilizing the ring gear/sungear tooth ratios of the planetary gear sets 20, 30 and 40.

The fifth forward speed ratio is established with the engagement of theclutch 56 and the brake 57. The clutch 56 connects the planet carrierassembly member 26 with the ring gear member 34. The brake 57 connectsthe ring gear member 24 with the transmission housing 60. The sun gearmember 22 and the sun gear member 32 rotate at the same speed as theinput shaft 17. The planet carrier assembly member 26 rotates at thesame speed as the ring gear member 34. The ring gear member 24 and thesun gear member 42 do not rotate. The speed of the planet carrierassembly member 26 is determined from the speed of the sun gear member22 and the ring gear/sun gear tooth ratio of the planetary gear set 20.The planet carrier assembly member 36 rotates at the same speed as theplanet carrier assembly member 46. The speed of the planet carrierassembly member 36 is determined from the speed of the ring gear member34, the speed of the sun gear member 32 and the ring gear/sun gear toothratio of the planetary gear set 30. The ring gear member 44 rotates atthe same speed as the output shaft 19. The ring gear member 44, andtherefore the output shaft 19, rotates at a speed determined from thespeed of the planet carrier assembly member 46 and the ring gear/sungear tooth ratio of the planetary gear set 40. The numerical value ofthe fifth forward speed ratio is determined utilizing the ring gear/sungear tooth ratios of the planetary gear sets 20, 30 and 40.

The sixth forward speed ratio is established with the engagement of theclutches 54 and 56. In this configuration, the input shaft 17 isdirectly connected with the output shaft 19. The numerical value of thesixth forward speed ratio is 1.

The seventh forward speed ratio is established with the engagement ofthe clutch 54 and the brake 57. The clutch 54 connects the sun gearmember 32 with the planet carrier assembly member 36. The brake 57connects the ring gear member 24 with the transmission housing 60. Thesun gear member 22, the planetary gear set 30 and the planet carrierassembly member 46 rotate at the same speed as the input shaft 17. Thering gear member 24 and the sun gear member 42 do not rotate. The ringgear member 44 rotates at the same speed as the output shaft 19. Thering gear member 44, and therefore the output shaft 19, rotates at aspeed determined from the speed of the planet carrier assembly member 46and the ring gear/sun gear tooth ratio of the planetary gear set 40. Thenumerical value of the seventh forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratio of the planetary gear set40.

The eighth forward speed ratio is established with the engagement of theclutch 54 and the brake 58. The clutch 54 connects the sun gear member32 with the planet carrier assembly member 36, and the brake 58 connectsthe planet carrier assembly member 26 with the transmission housing 60.The sun gear member 22, the planetary gear set 30 and the planet carrierassembly member 46 rotate at the same speed as the input shaft 17. Theplanet carrier assembly member 26 does not rotate. The ring gear member24 rotates at the same speed as the sun gear member 42. The ring gearmember 24 rotates at a speed determined from the speed of the sun gearmember 22 and the ring gear/sun gear tooth ratio of the planetary gearset 20. The ring gear member 44 rotates at the same speed as the outputshaft 19. The ring gear member 44, and therefore the output shaft 19,rotates at a speed determined from the speed of the planet carrierassembly member 46, the speed of the sun gear member 42 and the ringgear/sun gear tooth ratio of the planetary gear set 40. The numericalvalue of the eighth forward speed ratio is determined from the ringgear/sun gear tooth ratios of the planetary gear sets 20 and 40.

As set forth above, the engagement schedule for the torque-transmittingmechanisms is shown in the truth table of FIG. 1 b. This truth tablealso provides an example of speed ratios that are available utilizingthe ring gear/sun gear tooth ratios given by way of example in FIG. 1 b.The N_(R1)/S_(R1) value is the tooth ratio of the planetary gear set 20;the N_(R2)/S_(R2) value is the tooth ratio of the planetary gear set 30;and the N_(R3)/S_(R3) value is the tooth ratio of the planetary gear set40. Also, the chart of FIG. 1 b describes the ratio steps that areattained utilizing the sample of tooth ratios given. For example, thestep ratio between the first and second forward speed ratios is 1.99,while the step ratio between the second reverse speed ratio (R#2) andfirst forward ratio is −1.01. It should be noted that the single anddouble step forward ratio changes are of the single transition variety.The torque-transmitting mechanism 59 remains engaged through the neutralcondition, thus simplifying the forward/reverse interchange.

FIG. 2 a shows a powertrain 110 having a conventional engine and torqueconverter 12, a planetary transmission 114, and a conventional finaldrive mechanism 16.

The planetary transmission 114 includes an input shaft 17 continuouslyconnected with the engine and torque converter 12, a planetary geararrangement 118, and an output shaft 19 continuously connected with thefinal drive mechanism 16. The planetary gear arrangement 118 includesthree planetary gear sets 120, 130 and 140.

The planetary gear set 120 includes a sun gear member 122, a ring gearmember 124, and a planet carrier assembly 126. The planet carrierassembly 126 includes a plurality of pinion gears 127 rotatably mountedon a carrier member 129 and disposed in meshing relationship with boththe sun gear member 122 and the ring gear member 124.

The planetary gear set 130 includes a sun gear member 132, a ring gearmember 134, and a planet carrier assembly member 136. The planet carrierassembly member 136 includes a plurality of pinion gears 137 rotatablymounted on a carrier member 139 and disposed in meshing relationshipwith both the sun gear member 132 and the ring gear member 134.

The planetary gear set 140 includes a sun gear member 142, a ring gearmember 144, and a planet carrier assembly member 146. The planet carrierassembly member 146 includes a plurality of pinion gears 147 rotatablymounted on a carrier member 149 and disposed in meshing relationshipwith both the sun gear member 142 and the ring gear member 144.

The planetary gear arrangement 118 also includes seventorque-transmitting mechanisms 150, 152, 154, 156, 157, 158 and 159. Thetorque-transmitting mechanisms 150, 152, 154 and 156 are rotating-typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 157, 158 and 159 are stationary-typetorque-transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is continuously connected with the sun gear member122, and the output shaft 19 is continuously connected with the planetcarrier assembly member 136. The ring gear member 124 is continuouslyconnected with the planet carrier assembly member 146 through theinterconnecting member 170. The planet carrier assembly member 126 iscontinuously connected with the ring gear member 134 through theinterconnecting member 172. The sun gear member 132 is continuouslyconnected with the sun gear member 142 through the interconnectingmember 174.

The ring gear member 124 is selectively connectable with the planetcarrier assembly member 126 through the clutch 150. The ring gear member134 is selectively connectable with the ring gear member 144 through theclutch 152. The planet carrier assembly member 136 is selectivelyconnectable with the planet carrier assembly member 146 through theclutch 154. The planet carrier assembly member 136 is selectivelyconnectable with the ring gear member 144 through the clutch 156. Theplanet carrier assembly member 126 is selectively connectable with thetransmission housing 160 through the brake 157. The ring gear member 124is selectively connectable with the transmission housing 160 through thebrake 158. The sun gear member 142 is selectively connectable with thetransmission housing 160 through the brake 159.

The truth table of FIG. 2 b describes the engagement sequence utilizedto provide eight forward speed ratios and three reverse speed ratios inthe planetary gear arrangement 118 shown in FIG. 2 a.

The third reverse speed ratio (Reverse #3) is established with theengagement of the clutch 156 and the brake 157. The clutch 156 connectsthe planet carrier assembly member 136 with the ring gear member 144,and the brake 157 connects the planet carrier assembly member 126 withthe transmission housing 160. The sun gear member 122 rotates at thesame speed as the input shaft 17. The ring gear member 124 rotates atthe same speed as the planet carrier assembly member 146. The planetcarrier assembly member 126 and the ring gear member 134 do not rotate.The speed of the ring gear member 124 is determined from the speed ofthe sun gear member 122 and the ring gear/sun gear tooth ratio of theplanetary gear set 120. The sun gear member 132 rotates at the samespeed as the sun gear member 142. The planet carrier assembly member 136rotates at the same speed as the ring gear member 144. The speed of thering gear member 144 is determined from the speed of the planet carrierassembly member 146, the speed of the sun gear member 142 and the ringgear/sun gear tooth ratio of the planetary gear set 140. The planetcarrier assembly member 136 rotates at same speed as the output shaft19. The planet carrier assembly member 136, and therefore the outputshaft 19, rotates at a speed determined from the speed of the ring gearmember 134, the speed of the sun gear member 132 and the ring gear/sungear tooth ratio of the planetary gear set 130. The numerical value ofthe third reverse speed ration (Reverse #3) is determined utilizing thering gear/sun gear tooth ratios of the planetary gear sets 120, 130 and140.

The second reverse speed ratio (Reverse #2) is established with theengagement of the clutch 152 and the brake 157. The clutch 152 connectsthe ring gear member 134 with the ring gear member 144. The brake 157connects the planet carrier assembly member 126 with the transmissionhousing 160. The sun gear member 122 rotates at the same speed as theinput shaft 17. The ring gear member 124 rotates at the same speed asthe planet carrier assembly member 146. The planet carrier assemblymember 126, the ring gear member 134 and the ring gear member 144 do notrotate. The speed of the ring gear member 124 is determined from thespeed of the sun gear member 122 and the ring gear/sun gear tooth ratioof the planetary gear set 120. The sun gear member 142 rotates at thesame speed as the sun gear member 132. The speed of the sun gear member142 is determined from the speed of the planet carrier assembly member146 and the ring gear/sun gear tooth ratio of the planetary gear set140. The planet carrier assembly member 136 rotates at the same speed asthe output shaft 19. The planet carrier assembly member 136, andtherefore the output shaft 19, rotates at a speed determined from thespeed of the sun gear member 132 and the ring gear/sun gear tooth ratioof the planetary gear set 130. The numerical value of the second reversespeed ration (Reverse #2) is determined from the ring gear/sun geartooth ratios of the planetary gear sets 120, 130 and 140.

The first reverse speed ratio (Reverse #1) is established with theengagement of the clutch 154 and the brake 157. The clutch 154 connectsthe planet carrier assembly member 136 with the planet carrier assemblymember 146, and the brake 157 connects the planet carrier assemblymember 126 with the transmission housing 160. The sun gear member 122rotates at the same speed as the input shaft 17. The planet carrierassembly member 126 and the ring gear member 134 do not rotate. The ringgear 124 rotates at the same speed as the planetary gear set 140 and theplanet carrier assembly member 136. The planet carrier assembly member136 rotates at the same speed as the output shaft 19. The ring gearmember 124, and therefore the output shaft 19, rotates at a speeddetermined from the speed of the sun gear member 122 and the ringgear/sun gear tooth ratio of the planetary gear set 120. The numericalvalue of the first reverse speed ratio (Reverse #1) is determined fromthe ring gear/sun gear tooth ratio of the planetary gear set 120.

The first forward speed ratio is established with the engagement of theclutch 152 and the brake 158. The clutch 152 connects the ring gearmember 134 with the ring gear member 144, and the brake 158 connects thering gear member 124 with the transmission housing 160. The sun gearmember 122 rotates at the same speed as the input shaft 17. The planetcarrier assembly member 126 and the ring gear member 134 rotate at thesame speed as the ring gear member 144. The ring gear member 124 and theplanet carrier assembly member 146 do not rotate. The speed of theplanet carrier assembly member 126 is determined from the speed of thesun gear member 122 and the ring gear/sun gear tooth ratio of theplanetary gear set 120. The sun gear member 142 rotates at the samespeed as the sun gear member 132. The speed of the ring gear member 144is determined from the speed of the sun gear member 142 and the ringgear/sun gear tooth ratio of the planetary gear set 140. The planetcarrier assembly member 136 rotates at the same speed as the outputshaft 19. The planet carrier assembly member 136, and therefore theoutput shaft 19, rotates at a speed determined from the speed of thering gear member 134, the speed of the sun gear member 132 and the ringgear/sun gear tooth ratio of the planetary gear set 130. The numericalvalue of the first forward speed ratio is determined from the ringgear/sun gear tooth ratios of the planetary gear sets 120, 130 and 140.

The second forward speed ratio is determined with the engagement of theclutch 156 and the brake 158. The clutch 156 connects the planet carrierassembly member 136 with the ring gear member 144, and the brake 158connects the ring gear member 124 with the transmission housing 160. Thesun gear member 122 rotates at the same speed as the input shaft 17. Theplanet carrier assembly member 126 rotates at the same speed as the ringgear member 134. The ring gear member 124 and the planet carrierassembly member 146 do not rotate. The speed of the planet carrierassembly member 126 is determined from the speed of the sun gear member122 and the ring gear/sun gear tooth ratio of the planetary gear set120. The sun gear member 142 rotates at the same speed as the sun gearmember 132. The ring gear member 144 rotates at the same speed as theplanet carrier assembly member 136. The speed of the ring gear member144 is determined from the speed of the sun gear member 142 and the ringgear/sun gear tooth ratio of the planetary gear set 140. The planetcarrier assembly member 136 rotates at the same speed as the outputshaft 19. The planet carrier assembly member 136, and therefore theoutput shaft 19, rotates at a speed determined from the speed of thering gear member 134, the speed of the sun gear member 132 and the ringgear/sun gear tooth ratio of the planetary gear set 130. The numericalvalue of the second forward speed ratio is determined from the ringgear/sun gear tooth ratios of the planetary gear sets 120, 130 and 140.

The third forward speed ratio is established with the engagement of thebrake 158 and the brake 159. The brake 158 connects the ring gear member124 with the transmission housing 160, and the brake 159 connects thesun gear member 142 with the transmission housing 160. The sun gearmember 122 rotates the same speed as the input shaft 17. The planetcarrier assembly member 126 rotates at the same speed as the ring gearmember 134. The ring gear member 124 and the planet carrier assemblymember 146 do not rotate. The speed of the planet carrier assemblymember 126 is determined from the speed of the sun gear member 122 andthe ring gear/sun gear tooth ratio of the planetary gear set 120. Thesun gear member 132 and the ring gear member 142 do not rotate. Theplanet carrier assembly member 136 rotates at the same speed as theoutput shaft 19. The planet carrier assembly member 136, and thereforethe output shaft 19, rotates at a speed determined from the speed of thering gear member 134 and the ring gear/sun gear tooth ratio of theplanetary gear set 130. The numerical value of the third forward speedratio is determined from the ring gear/sun gear tooth ratios of theplanetary gear sets 120 and 130.

The fourth forward speed ratio is established with the engagement of theclutch 156 and the brake 159. The clutch 156 connects the planet carrierassembly member 136 with the ring gear member 144, and the brake 159connects the sun gear member 142 with the transmission housing 160. Thesun gear member 122 rotates at the same speed as the input shaft 17. Theplanet carrier assembly member 126 rotates at the same speed as the ringgear member 134. The ring gear member 124 rotates at same speed as theplanet carrier assembly member 146. The speed of the ring gear member124 is determined from the speed of the planet carrier assembly member126, the speed of the sun gear member 122 and the ring gear/sun geartooth ratio of the planetary gear set 120. The ring gear member 144rotates at the same speed as the planet carrier assembly member 136. Thesun gear member 142 and the sun gear member 132 do not rotate. The speedof the ring gear member 144 is determined from the speed of the planetcarrier assembly member 146 and the ring gear/sun gear tooth ratio ofthe planetary gear set 140. The planet carrier assembly member 136rotates at the same speed as the output shaft 19. The planet carrierassembly member 136, and therefore the output shaft 19, rotates at aspeed determined from the speed of the ring gear member 134 and the ringgear/sun gear tooth ratio of the planetary gear set 130. The numericalvalue of the fourth forward speed ratio is determined utilizing the ringgear/sun gear tooth ratios of the planetary gear sets 120, 130, 140.

The fifth forward speed ratio is established with the engagement of theclutch 152 and the brake 159. The clutch 152 connects the ring gearmember 134 and the ring gear member 144, and the brake 159 connects thesun gear member 142 with the transmission housing 160. The sun gearmember 122 rotates at the same speed as the input shaft 17. The ringgear member 124 rotates at the same speed as the planet carrier assemblymember 146. The planet carrier assembly member 126 and the ring gearmember 134 rotate at the same speed as the ring gear member 144. Thespeed of the ring gear member 124 is determined from the speed of theplanet carrier assembly member 126, the speed of the sun gear member 122and the ring gear/sun gear tooth ratio of the planetary gear set 120.The sun gear member 142 and the sun gear member 132 do not rotate. Thespeed of the ring gear member 144 is determined from the speed of theplanet carrier assembly member 146 and the ring gear/sun gear toothratio of the planetary gear set 140. The planet carrier assembly member136 rotates at the same speed as the output shaft 19. The planet carrierassembly member 136, and therefore the output shaft 19, rotates at aspeed determined from the speed of the ring gear member 134 and the ringgear/sun gear tooth ratio of the planetary gear set 130. The numericalvalue of the fifth forward speed ratio is determined utilizing the ringgear/sun gear tooth ratios of the planetary gear sets 120, 130 and 140.

The sixth forward speed ratio is established with the engagement of theclutch 154 and the brake 159. The clutch 154 connects the planet carrierassembly member 136 with the planet carrier assembly member 146, and thebrake 159 connects the sun gear member 142 with the transmission housing160. The sun gear member 122 rotates at the same speed as the inputshaft 17. The planet carrier assembly member 126 rotates at the samespeed as the ring gear member 134. The ring gear member 124 and theplanet carrier assembly member 146 rotate at the same speed as theplanet carrier assembly member 136. The speed of the ring gear member124 is determined from the speed of the planet carrier assembly member126, the speed of the sun gear member 122 and the ring gear/sun geartooth ratio of the planetary gear set 120. The sun gear member 132 andthe sun gear member 142 do not rotate. The planet carrier assemblymember 136 rotates at the same speed as the output shaft 19. The planetcarrier assembly member 136, and therefore the output shaft 19, rotatesat a speed determined from the speed of the ring gear member 134 and thering gear/sun gear tooth ratio of the planetary gear set 130. Thenumerical value of the sixth forward speed ratio is determined utilizingthe ring gear/sun gear tooth ratios of the planetary gear sets 120 and130.

The seventh forward speed ratio is established with the engagement ofthe clutch 150 and the brake 159. The clutch 150 connects the planetcarrier assembly member 126 with the ring gear member 124, and the brake159 connects the sun gear member 142 with the transmission housing 160.The sun gear member 122 rotates at the same speed as the input shaft 17.The planet carrier assembly member 126, the ring gear member 124 and theplanet carrier assembly member 146 rotate at the same speed as the ringgear member 134. The sun gear member 132 and the sun gear member 142 donot rotate. The planet carrier assembly member 136 rotates at the samespeed as the output shaft 19. The planet carrier assembly member 136,and therefore the output shaft 19, rotates at a speed determined fromthe speed of the ring gear member 134 and the ring gear/sun gear toothratio of the planetary gear set 130. The numerical value of the seventhforward speed ratio is determined utilizing the ring gear/sun gear toothratio of the planetary gear set 130.

The eighth forward speed ratio is established with the engagement of theclutches 150 and 152. In this configuration, the input shaft 17 isdirectly connected to the output shaft 19. The numerical value of theeighth forward speed ratio is 1.

As set forth above, the truth table of FIG. 2 b describes the engagementsequence of the torque-transmitting mechanisms utilized to provide threereverse speed ratios and eight forward speed ratios. The truth tablealso provides an example of the ratios that can be attained with thefamily members shown in FIG. 2 a utilizing the sample tooth ratios givenin FIG. 2 b. The N_(R1)/S_(R1) value is the tooth ratio of the planetarygear set 120; the N_(R2)/S_(R2) value is the tooth ratio of theplanetary gear set 130; and the N_(R3)/S_(R3) value is the tooth ratioof the planetary gear set 140. Also shown in FIG. 2 b are the ratiosteps between single step ratios in the forward direction as well as thethird reverse (Reverse #3) to first ratio step. For example, the firstto second step ratio is 1.73. It should also be noted that the singlestep forward ratio interchanges are of the single transition variety.

Turning to FIG. 3 a, a powertrain 210 includes the engine and torqueconverter 12, a planetary transmission 214, and a final drive mechanism16. The planetary transmission 214 includes an input shaft 17continuously connected with the engine and torque converter 12, aplanetary gear arrangement 218, and an output shaft 19 continuouslyconnected with the final drive mechanism 16. The planetary geararrangement 218 includes three planetary gear sets 220, 230 and 240.

The planetary gear set 220 includes a sun gear member 222, a ring gearmember 224, and a planet carrier assembly 226. The planet carrierassembly 226 includes a plurality of pinion gears 227 rotatably mountedon a carrier member 229 and disposed in meshing relationship with boththe sun gear member 222 and the ring gear member 224.

The planetary gear set 230 includes a sun gear member 232, a ring gearmember 234, and a planet carrier assembly member 236. The planet carrierassembly member 236 includes a plurality of pinion gears 237 rotatablymounted on a carrier member 239 and disposed in meshing relationshipwith both the sun gear member 232 and the ring gear member 234.

The planetary gear set-240 includes a sun gear member 242, a ring gearmember 244, and a planet carrier assembly member 246. The planet carrierassembly member 246 includes a plurality of pinion gears 247 rotatablymounted on a carrier member 249 and disposed in meshing relationshipwith both the sun gear member 242 and the ring gear member 244.

The planetary gear arrangement 218 also includes seventorque-transmitting mechanisms 250, 252, 254, 256, 257, 258 and 259. Thetorque-transmitting mechanisms 250, 252 and 254 are rotating typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 256, 257, 258 and 259 are stationary-typetorque-transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is continuously connected with the planet carrierassembly member 226, and the output shaft 19 is continuously connectedwith the planet carrier assembly member 246. The planet carrier assemblymember 226 is continuously connected with the sun gear member 232through the interconnecting member 270. The sun gear member 222 iscontinuously connected with the sun gear member 242 through theinterconnecting member 272. The planet carrier assembly member 236 iscontinuously connected with the ring gear member 244 through theinterconnecting member 274.

The planet carrier assembly member 226 is selectively connectable withthe planet carrier assembly member 236 through the clutch 250. The ringgear member 224 is selectively connectable with the planet carrierassembly member 236 through the clutch 252. The ring gear member 234 isselectively connectable with the planet carrier assembly member 246through the clutch 254. The planet carrier assembly member 236 isselectively connectable with the transmission housing 260 through thebrake 256. The ring gear member 234 is selectively connectable with thetransmission housing 260 through the brake 257. The ring gear member 224is selectively connectable with the transmission housing 260 through thebrake 258. The sun gear member 222 is selectively connectable with thetransmission housing 260 through the brake 259.

As shown in the truth table in FIG. 3 b, the torque-transmittingmechanisms are engaged in combinations of two to establish ten forwardspeed ratios and one reverse ratio.

The truth tables given in FIGS. 3 b, 4 b, 5 b, 6 b, 7 b, 8 b, 9 b, 10 b,and 11 b show the engagement sequences for the torque-transmittingmechanisms to provide at least eight forward speed ratios and at leastone reverse ratio. As shown and described above for the configurationsin FIGS. 1 a and 2 a, those skilled in the art will understand from therespective truth tables how the speed ratios are established through theplanetary gear sets identified in the written description.

As previously set forth, the truth table of FIG. 3 b describes thecombinations of engagements utilized for the ten forward speed ratiosand one reverse ratio. The truth table also provides an example of speedratios that are available with the family member described above. Theseexamples of speed ratios are determined utilizing the tooth ratios givenin FIG. 3 b. The N_(R1)/S_(R1) value is the tooth ratio of the planetarygear set 220; the N_(R2)/S_(R2) value is the tooth ratio of theplanetary gear set 230; and the N_(R3)/S_(R3) value is the tooth ratioof the planetary gear set 240. Also depicted in FIG. 3 b is a chartrepresenting the ratio steps between adjacent forward speed ratios andthe reverse speed ratio. For example, the first to second ratiointerchange has a step of 1.78. It can also be readily determined fromthe truth table of FIG. 3 b that all of the single step and double stepforward ratio interchanges are of the single transition variety.

A powertrain 310, shown in FIG. 4 a, includes the engine and torqueconverter 12, a planetary transmission 314, and the final drivemechanism 16. The planetary transmission 314 includes an input shaft 17continuously connected with the engine and torque converter 12, aplanetary gear arrangement 318, and output shaft 19 continuouslyconnected with the final drive mechanism 16. The planetary geararrangement 318 includes three planetary gear sets 320, 330 and 340.

The planetary gear set 320 includes a sun gear member 322, a ring gearmember 324, and a planet carrier assembly member 326. The planet carrierassembly member 326 includes a plurality of pinion gears 327 rotatablymounted on a carrier member 329 and disposed in meshing relationshipwith both the sun gear member 322 and the ring gear member 324.

The planetary gear set 330 includes a sun gear member 332, a ring gearmember 334, and a planet carrier assembly member 336. The planet carrierassembly member 336 includes a plurality of pinion gears 337 rotatablymounted on a carrier member 339 and disposed in meshing relationshipwith both the sun gear member 332 and the ring gear member 334.

The planetary gear set 340 includes a sun gear member 342, a ring gearmember 344, and a planet carrier assembly member 346. The planet carrierassembly member 346 includes a plurality of pinion gears 347 rotatablymounted on a carrier member 349 and disposed in meshing relationshipwith both the sun gear member 342 and the ring gear member 344.

The planetary gear arrangement 318 also includes seventorque-transmitting mechanisms 350, 352, 354, 356, 357, 358 and 359. Thetorque-transmitting mechanisms 350, 352, 354 and 356 are rotating typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 357, 358 and 359 are stationary-typetorque-transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is continuously connected with the sun gear member322, and the output shaft 19 is continuously connected with the ringgear member 344. The planet carrier assembly member 326 is continuouslyconnected with the ring gear member 334 through the interconnectingmember 370. The ring gear member 324 is continuously connected with thesun gear member 342 through the interconnecting member 372. The planetcarrier assembly member 336 is continuously connected with the planetcarrier assembly member 346 through the interconnecting member 374.

The planet carrier assembly member 326 is selectively connectable withthe sun gear member 322 through the clutch 350. The sun gear member 322is selectively connectable with the planet carrier assembly member 336through the clutch 352. The sun gear member 322 is selectivelyconnectable with the sun gear member 332 through the clutch 354. The sungear member 332 is selectively connectable with the ring gear member 344through the clutch 356. The planet carrier assembly member 326 isselectively connectable with the transmission housing 360 through thebrake 357. The ring gear member 324 is selectively connectable with thetransmission housing 360 through the brake 358. The planet carrierassembly member 346 is selectively connectable with the transmissionhousing 360 through the brake 359.

The truth table shown in FIG. 4 b describes the engagement combinationand the engagement sequence necessary to provide a reverse drive ratio,eight forward speed ratios (as well as an extra fourth forward speedratio (4′) and an extra fifth forward speed ratio (5′)). A sample of thenumerical values for the ratios is also provided in the truth table ofFIG. 4 b. These values are determined utilizing the ring gear/sun geartooth ratios also given in FIG. 4 b. The N_(R1)/S_(R1) value is thetooth ratio for the planetary gear set 320; the N_(R1)/S_(R2) value isthe tooth ratio for the planetary gear set 330; and the N_(R3)/S_(R3)value is the tooth ratio for the planetary gear set 340. Also given inFIG. 4 b is a chart describing the step ratios between the adjacentforward speed ratios and the reverse to first forward speed ratio. Forexample, the first to second forward speed ratio step is 1.52. It can bereadily determined from the truth table of FIG. 4 b that each of theforward single step ratio interchanges is a single transition shift.Additionally, the torque-transmitting mechanism 359 remains engagedthrough the neutral condition, thus simplifying the forward/reverseinterchange.

A powertrain 410, shown in FIG. 5 a, includes the engine and torqueconverter 12, a planetary transmission 414 and the final drive mechanism16. The planetary transmission 414 includes a planetary gear arrangement418, input shaft 17 and output shaft 19. The planetary gear arrangement418 includes three simple planetary gear sets 420, 430 and 440.

The planetary gear set 420 includes a sun gear member 422, a ring gearmember 424, and a planet carrier assembly 426. The planet carrierassembly 426 includes a plurality of pinion gears 427 rotatably mountedon a carrier member 429 and disposed in meshing relationship with boththe sun gear member 422 and the ring gear member 424.

The planetary gear set 430 includes a sun gear member 432, a ring gearmember 434, and a planet carrier assembly member 436. The planet carrierassembly member 436 includes a plurality of pinion gears 437 rotatablymounted on a carrier member 439 and disposed in meshing relationshipwith both the sun gear member 432 and the ring gear member 434.

The planetary gear set 440 includes a sun gear member 442, a ring gearmember 444, and a planet carrier assembly member 446. The planet carrierassembly member 446 includes a plurality of pinion gears 447 rotatablymounted on a carrier member 449 and disposed in meshing relationshipwith both the sun gear member 442 and the ring gear member 444.

The planetary gear arrangement 418 also includes seventorque-transmitting mechanisms 450, 452, 454, 456, 457, 458 and 459. Thetorque-transmitting mechanisms 450, 452, 454 and 456 are rotating typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 457, 458 and 459 are stationary-typetorque-transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is continuously connected with the sun gear member432, and the output shaft 19 is continuously connected with the planetcarrier assembly member 426. The sun gear member 422 is continuouslyconnected with the ring gear member 444 through the interconnectingmember 470. The ring gear member 424 is continuously connected with theplanet carrier assembly member 436 through the interconnecting member472. The ring gear member 434 is continuously connected with the planetcarrier assembly member 446 through the interconnecting member 474.

The planet carrier assembly member 436 is selectively connectable withthe sun gear member 432 through the clutch 450. The planet carrierassembly member 436 is selectively connectable with the sun gear member442 through the clutch 452. The planet carrier assembly member 426 isselectively connectable with the ring gear member 434 through the clutch454. The sun gear member 432 is selectively connectable with the sungear member 442 through the clutch 456. The planet carrier assemblymember 446 is selectively connectable with the transmission housing 460through the brake 457. The sun gear member 422 is selectivelyconnectable with the transmission housing 460 through the brake 458. Thesun gear member 442 is selectively connectable with the transmissionhousing 460 through the brake 459.

The truth table shown in FIG. 5 b describes the engagement combinationand sequence of the torque-transmitting mechanisms 450, 452, 454, 456,457, 458 and 459 that are employed to provide the reverse drive ratioand nine forward speed ratios (as well as an extra second forward speedratio (2′)).

Also given in the truth table of FIG. 5 b is a set of numerical valuesthat are attainable with the present invention utilizing the ringgear/sun gear tooth ratios shown. The N_(R1)/S_(R1) value is the toothratio of the planetary gear set 420; the N_(R2)/S_(R2) value is thetooth ratio of the planetary gear set 430; and the N_(R3)/S_(R3) valueis the tooth ratio of the planetary gear set 440. As can also bedetermined from the truth table of FIG. 5 b, all of the single stepforward interchanges are of the single transition variety.

FIG. 5 b also provides a chart of the ratio steps between adjacentforward ratios and between the reverse ratio and first forward ratio.For example, the ratio step between the first and second forward ratiosis 1.57.

A powertrain 510, shown in FIG. 6 a, includes an engine and torqueconverter 12, a planetary gear transmission 514 and the final drivemechanism 16. The planetary transmission 514 includes the input shaft17, a planetary gear arrangement 518 and the output shaft 19. Theplanetary gear arrangement 518 includes three planetary gear sets 520,530 and 540.

The planetary gear set 520 includes a sun gear member 522, a ring gearmember 524, and a planet carrier assembly 526. The planet carrierassembly 526 includes a plurality of pinion gears 527 rotatably mountedon a carrier member 529 and disposed in meshing relationship with boththe sun gear member 522 and the ring gear member 524.

The planetary gear set 530 includes a sun gear member 532, a ring gearmember 534, and a planet carrier assembly member 536. The planet carrierassembly member 536 includes a plurality of pinion gears 537 rotatablymounted on a carrier member 539 and disposed in meshing relationshipwith both the sun gear member 532 and the ring gear member 534.

The planetary gear set 540 includes a sun gear member 542, a ring gearmember 544, and a planet carrier assembly member 546. The planet carrierassembly member 546 includes a plurality of pinion gears 547 rotatablymounted on a carrier member 549 and disposed in meshing relationshipwith both the sun gear member 542 and the ring gear member 544.

The planetary gear arrangement 518 also includes seventorque-transmitting mechanisms 550, 552, 554, 556, 557, 558 and 559. Thetorque-transmitting mechanisms 550, 552, 554 and 556 are rotating typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 557, 558 and 559 are stationary-typetorque-transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is continuously connected with the sun gear member532, and the output shaft 19 is continuously connected with the ringgear member 544. The planet carrier assembly member 526 is continuouslyconnected with the planet carrier assembly member 546 through theinterconnecting member 570. The ring gear member 524 is continuouslyconnected with the planet carrier assembly member 536 through theinterconnecting member 572. The ring gear member 534 is continuouslyconnected with the sun gear member 542 through the interconnectingmember 574.

The sun gear member 532 is selectively connectable with the planetcarrier assembly member 526 through the clutch 550. The sun gear member542 is selectively connectable with the planet carrier assembly member546 through the clutch 552. The sun gear member 522 is selectivelyconnectable with the sun gear member 532 through the clutch 554. Thering gear member 544 is selectively connectable with the sun gear member522 through the clutch 556. The planet carrier assembly member 536 isselectively connectable with the transmission housing 560 through thebrake 557. The planet carrier assembly member 546 is selectivelyconnectable with the transmission housing 560 through the brake 558. Thesun gear member 542 is selectively connectable with the transmissionhousing 560 through the brake 559.

The truth table shown in FIG. 6 b describes the engagement sequence andcombination of the torque-transmitting mechanisms to provide the reversespeed ratio and eight forward speed ratios (as well as an extra fourthspeed ratio (4′) and an extra fifth speed ratio (5′)). It should benoted that the torque-transmitting mechanism 557 remains engaged throughthe neutral condition, thereby simplifying the forward/reverseinterchange. The chart of FIG. 6 b describes the ratio steps betweenadjacent forward speed ratios and the ratio step between the reverse andfirst forward speed ratio.

The sample speed ratios given in the truth table are determinedutilizing the tooth ratio values also given in FIG. 6 b. TheN_(R1)/S_(R1) value is the tooth ratio of the planetary gear set 520;the N_(R2)/S_(R2) value is the tooth ratio of the planetary gear set530; and the N_(R3)/S_(R3) value is the tooth ratio of the planetarygear set 540. As can also be determined from the truth table of FIG. 6b, each of the single step forward interchanges is of the singletransition variety.

A powertrain 610, shown in FIG. 7 a, has the engine and torque converter12, a planetary transmission 614 and the final drive mechanism 16. Theplanetary transmission 614 includes the input shaft 17, a planetary geararrangement 618 and the output shaft 19. The planetary gear arrangement618 includes three planetary gear sets 620, 630 and 640.

The planetary gear set 620 includes a sun gear member 622, a ring gearmember 624, and a planet carrier assembly 626. The planet carrierassembly 626 includes a plurality of pinion gears 627 rotatably mountedon a carrier member 629 and disposed in meshing relationship with boththe sun gear member 622 and the ring gear member 624.

The planetary gear set 630 includes a sun gear member 632, a ring gearmember 634, and a planet carrier assembly member 636. The planet carrierassembly member 636 includes a plurality of pinion gears 637 rotatablymounted on a carrier member 639 and disposed in meshing relationshipwith both the sun gear member 632 and the ring gear member 634.

The planetary gear set 640 includes a sun gear member 642, a ring gearmember 644, and a planet carrier assembly member 646. The planet carrierassembly member 646 includes a plurality of pinion gears 647 rotatablymounted on a carrier member 649 and disposed in meshing relationshipwith both the sun gear member 642 and the ring gear member 644.

The planetary gear arrangement 618 also includes seventorque-transmitting mechanisms 650, 652, 654, 656, 657, 658 and 659. Thetorque-transmitting mechanisms 650, 652, 654 and 656 are rotating typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 657, 658 and 659 are stationary-typetorque-transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is continuously connected with the planet carrierassembly member 626, and the output shaft 19 is continuously connectedwith the planet carrier assembly member 646. The ring gear member 624 iscontinuously connected with the sun gear member 642 through theinterconnecting member 670. The sun gear member 622 is continuouslyconnected with the sun gear member 632 through the interconnectingmember 672. The ring gear member 634 is continuously connected with theplanet carrier assembly member 646 through the interconnecting member674.

The planet carrier assembly member 626 is selectively connectable withthe ring gear member 624 through the clutch 650. The planet carrierassembly member 646 is selectively connectable with the sun gear member642 through the clutch 652. The planet carrier assembly member 636 isselectively connectable with the sun gear member 642 through the clutch654. The ring gear member 644 is selectively connectable with the planetcarrier assembly member 636 through the clutch 656. The sun gear member622 is selectively connectable with the transmission housing 660 throughthe brake 657. The ring gear member 644 is selectively connectable withthe transmission housing 660 through the brake 658. The planet carrierassembly member 636 is selectively connectable with the transmissionhousing 660 through the brake 659.

The truth table shown in FIG. 7 b describes the combination oftorque-transmitting mechanism engagements that will provide the threereverse drive ratios and eight forward speed ratios, as well as thesequence of these engagements and interchanges.

The ratio values given are by way of example and are establishedutilizing the ring gear/sun gear tooth ratios given in FIG. 7 b. Forexample, the N_(R1)/S_(R1) value is the tooth ratio of the planetarygear set 620; the N_(R2)/S_(R2) value is the tooth ratio of theplanetary gear set 630; and the N_(R3)/S_(R3) value is the tooth ratioof the planetary gear set 640. The ratio steps between adjacent forwardratios and the third reverse to first ratio are also given in FIG. 7 b.For example, the ratio step between the first and second forward ratiois 1.67. As can also be determined from the truth table of FIG. 7 b,each of the single step forward interchanges are of the singletransition variety.

A powertrain 710, shown in FIG. 8 a, has the conventional engine andtorque converter 12, a planetary transmission 714, and the conventionalfinal drive mechanism 16. The engine and torque converter 12 aredrivingly connected with the planetary transmission 714 through theinput shaft 17. The planetary transmission 714 is drivingly connectedwith the final drive mechanism 16 through the output shaft 19. Theplanetary transmission 714 includes a planetary gear arrangement 718that has a first planetary gear set 720, a second planetary gear set730, and a third planetary gear set 740.

The planetary gear set 720 includes a sun gear member 722, a ring gearmember 724, and a planet carrier assembly 726. The planet carrierassembly 726 includes a plurality of pinion gears 727 rotatably mountedon a carrier member 729 and disposed in meshing relationship with boththe sun gear member 722 and the ring gear member 724.

The planetary gear set 730 includes a sun gear member 732, a ring gearmember 734, and a planet carrier assembly member 736. The planet carrierassembly member 736 includes a plurality of pinion gears 737 rotatablymounted on a carrier member 739 and disposed in meshing relationshipwith both the sun gear member 732 and the ring gear member 734.

The planetary gear set 740 includes a sun gear member 742, a ring gearmember 744, and a planet carrier assembly member 746. The planet carrierassembly member 746 includes a plurality of pinion gears 747 rotatablymounted on a carrier member 749 and disposed in meshing relationshipwith the sun gear member 742. Pinion gears 748 are disposed in meshingrelationship with both the ring gear member 744 and the pinion gears747.

The planetary gear arrangement 718 also includes seventorque-transmitting mechanisms 750, 752, 754, 756, 757, 758 and 759. Thetorque-transmitting mechanisms 750, 752, 754 and 756 are rotating typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 757, 758 and 759 are stationary-typetorque-transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is continuously connected with the planet carrierassembly member 736, and the output shaft 19 is continuously connectedwith the ring gear member 744. The ring gear member 724 is continuouslyconnected with the planet carrier assembly member 736 through theinterconnecting member 770. The sun gear member 722 is continuouslyconnected with the sun gear member 742 through the interconnectingmember 772. The sun gear member 732 is continuously connected with thering gear member 744 through the interconnecting member 774.

The planet carrier assembly member 726 is selectively connectable withthe sun gear member 722 through the clutch 750. The ring gear member 734is selectively connectable with the sun gear member 722 through theclutch 752. The ring gear member 734 is selectively connectable with theplanet carrier assembly member 726 through the clutch 754. The planetcarrier assembly member 726 is selectively connectable with the sun gearmember 732 through the clutch 756. The sun gear member 722 isselectively connectable with the transmission housing 760 through thebrake 757. The ring gear member 734 is selectively connectable with thetransmission housing 760 through the brake 758. The planet carrierassembly member 746 is selectively connectable with the transmissionhousing 760 through the brake 759.

The truth table of FIG. 8 b defines the torque-transmitting mechanismengagement sequence utilized for each of the nine forward speed ratiosand the reverse speed ratio (as well as the extra second speed ratio(2′)). Also given in the truth table is a set of numerical values thatare attainable with the present invention utilizing the ring gear/sungear tooth ratios given in FIG. 8 b. The N_(R1)/S_(R1) value is thetooth ratio of the planetary gear set 720; the N_(R2)/S_(R2) value isthe tooth ratio of the planetary gear set 730; and the N_(R3)/S_(R3)value is the tooth ratio of the planetary gear set 740. As may bedetermined from the truth table of FIG. 8 b, each of the single stepforward interchanges is of the single transition variety. Additionally,the torque-transmitting mechanism 759 remains engaged through theneutral condition, thus simplifying the forward/reverse interchange.

FIG. 8 b also provides a chart of the ratio steps between adjacentforward ratios and between the reverse and first forward ratio. Forexample, the ratio step between the first and second forward ratios is1.54.

A powertrain 810, shown in FIG. 9 a, has the conventional engine andtorque converter 12, a planetary transmission 814, and the final drivemechanism 16. The engine and torque converter 12 are drivingly connectedwith the planetary transmission 814 through the input shaft 17. Theplanetary transmission 814 is drivingly connected with the final drivemechanism 16 through the output shaft 19. The planetary transmission 814includes a planetary gear arrangement 818 that has a first planetarygear set 820, a second planetary gear set 830, and a third planetarygear set 840.

The planetary gear set 820 includes a sun gear member 822, a ring gearmember 824, and a planet carrier assembly 826. The planet carrierassembly 826 includes a plurality of pinion gears 827 rotatably mountedon a carrier member 829 and disposed in meshing relationship with boththe sun gear member 822 and the ring gear member 824.

The planetary gear set 830 includes a sun gear member 832, a ring gearmember 834, and a planet carrier assembly member 836. The planet carrierassembly member 836 includes a plurality of pinion gears 837 rotatablymounted on a carrier member 839 and disposed in meshing relationshipwith both the sun gear member 832 and the ring gear member 834.

The planetary gear set 840 includes a sun gear member 842, a ring gearmember 844, and a planet carrier assembly member 846. The planet carrierassembly member 846 includes a plurality of pinion gears 847 rotatablymounted on a carrier member 849 and disposed in meshing relationshipwith both the sun gear member 842 and the ring gear member 844.

The planetary gear arrangement 818 also includes seventorque-transmitting mechanisms 850, 852, 854, 856, 857, 858 and 859. Thetorque-transmitting mechanisms 850, 852 and 854 are rotating typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 856, 857, 858 and 859 are stationary-typetorque-transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is continuously connected with the sun gear member842, and the output shaft 19 is continuously connected with the ringgear member 824. The planet carrier assembly member 826 is continuouslyconnected with the planet carrier assembly member 836 through theinterconnecting member 870. The ring gear member 834 is continuouslyconnected with the planet carrier assembly member 846 through theinterconnecting member 872. The sun gear member 822 is continuouslyconnected with the ring gear member 844 through the interconnectingmember 874.

The sun gear member 822 is selectively connectable with the planetcarrier assembly member 826 through the clutch 850. The planet carrierassembly member 836 is selectively connectable with the sun gear member842 through the clutch 852. The sun gear member 842 is selectivelyconnectable with the planet carrier assembly member 846 through theclutch 854. The planet carrier assembly member 826 is selectivelyconnectable with the transmission housing 860 through the brake 856. Thering gear member 844 is selectively connectable with the transmissionhousing 860 through the brake 857. The sun gear member 832 isselectively connectable with the transmission housing 860 through thebrake 858. The planet carrier assembly member 846 is selectivelyconnectable with the transmission housing 860 through the brake 859.

The truth table shown in FIG. 9 b defines the torque-transmittingmechanism engagement sequence that provides the two reverse speed ratiosand eight forward speed ratios shown in the truth table and availablewith the planetary gear arrangement 818. A sample of numerical valuesfor the individual ratios is also given in the truth table of FIG. 9 b.These numerical values have been calculated using the ring gear/sun geartooth ratios also given by way of example in FIG. 9 b. The N_(R1)/S_(R1)value is the tooth ratio of the planetary gear set 820; theN_(R2)/S_(R2) value is the tooth ratio of the planetary gear set 830;and the N_(R3)/S_(R3) value is the tooth ratio of the planetary gear set840. It can be readily recognized from the truth table that all of thesingle step forward interchanges are of the single transition variety.FIG. 9 b also describes the ratio steps between adjacent forward ratiosand between the second reverse and first forward ratio. For example, theratio step between the first and second forward ratios is 1.96.

The powertrain 910, shown in FIG. 10 a, includes the conventional engineand torque converter 12, a planetary transmission 914, and theconventional final drive mechanism 16. The engine and torque converter12 are drivingly connected with the planetary transmission 914 throughthe input shaft 17. The planetary transmission 914 is drivinglyconnected with the final drive mechanism 16 through the output shaft 19.The planetary transmission 914 includes a planetary gear arrangement 918that has a first planetary gear set 920, a second planetary gear set930, and a third planetary gear set 940.

The planetary gear set 920 includes a sun gear member 922, a ring gearmember 924, and a planet carrier assembly 926. The planet carrierassembly 926 includes a plurality of pinion gears 927 that are rotatablymounted on a carrier member 929 and disposed in meshing relationshipwith the sun gear member 922 and the ring gear member 924, respectively.

The planetary gear set 930 includes a sun gear member 932, a ring gearmember 934, and a planet carrier assembly member 936. The planet carrierassembly member 936 includes a plurality of pinion gears 937 rotatablymounted on a carrier member 939 and disposed in meshing relationshipwith both the sun gear member 932 and the ring gear member 934.

The planetary gear set 940 includes a sun gear member 942, a ring gearmember 944, and a planet carrier assembly member 946. The planet carrierassembly member 946 includes a plurality of pinion gears 947 rotatablymounted on a carrier member 949 and disposed in meshing relationshipwith the sun gear member 942. Pinion gears 938 are disposed in meshingrelationship with both the ring gear member 944 and the pinion gears937.

The planetary gear arrangement 918 also includes seventorque-transmitting mechanisms 950, 952, 954, 956, 957, 958 and 959. Thetorque-transmitting mechanisms 950, 952 and 954 are rotating typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 956, 957, 958 and 959 are stationary-typetorque-transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is continuously connected with the planet carrierassembly member 926, and the output shaft 19 is continuously connectedwith the ring gear member 944. The planet carrier assembly member 926 iscontinuously connected with the sun gear member 932 through theinterconnecting member 970. The sun gear member 922 is continuouslyconnected with the sun gear member 942 through the interconnectingmember 972. The planet carrier assembly member 936 is continuouslyconnected with the planet carrier assembly member 946 through theinterconnecting member 974.

The planet carrier assembly member 926 is selectively connectable withthe planet carrier assembly member 936 through the clutch 950. The ringgear member 924 is selectively connectable with the planet carrierassembly member 936 through the clutch 952. The ring gear member 934 isselectively connectable with the ring gear member 944 through the clutch954. The planet carrier assembly member 936 is selectively connectablewith the transmission housing 960 through the brake 956. The ring gearmember 934 is selectively connectable with the transmission housing 960through the brake 957. The ring gear member 924 is selectivelyconnectable with the transmission housing 960 through the brake 958. Thesun gear member 922 is selectively connectable with the transmissionhousing 960 through the brake 959.

The truth table of FIG. 10 b describes the torque-transmitting mechanismengagement sequence utilized to provide a reverse speed ratio and tenforward speed ratios. The truth table also provides a set of examplesfor the ratios for each of the reverse and forward speed ratios. Thesenumerical values have been determined utilizing the ring gear/sun geartooth ratios given in FIG. 10 b. The N_(R1)/S_(R1) value is the toothratio of the planetary gear set 920; the N_(R2)/S_(R2) value is thetooth ratio of the planetary gear set 930; and the N_(R3)/S_(R3) valueis the tooth ratio of the planetary gear set 940. As can also bedetermined from the truth table of FIG. 10 b, each of the single stepand double step forward interchanges are of the single transitionvariety.

A powertrain 1010, shown in FIG. 11 a, includes the conventional engineand torque converter 12, a planetary transmission 1014, and theconventional final drive mechanism 16. The engine and torque converterare drivingly connected with the planetary transmission 1014 through theinput shaft 17. The planetary transmission 1014 is drivingly connectedwith the final drive mechanism 16 through the output shaft 19. Theplanetary transmission 1014 includes a planetary gear arrangement 1018that has a first planetary gear set 1020, a second planetary gear set1030, and a third planetary gear set 1040.

The planetary gear set 1020 includes a sun gear member 1022, a ring gearmember 1024, and a planet carrier assembly 1026. The planet carrierassembly 1026 includes a plurality of pinion gears 1027 rotatablymounted on a carrier member 1029 and disposed in meshing relationshipwith both the sun gear member 1022 and the ring gear member 1024.

The planetary gear set 1030 includes a sun gear member 1032, a ring gearmember 1034, and a planet carrier assembly member 1036. The planetcarrier assembly member 1036 includes a plurality of pinion gears 1037rotatably mounted on a carrier member 1039 and disposed in meshingrelationship with both the sun gear member 1032 and the ring gear member1034.

The planetary gear set 1040 includes a sun gear member 1042, a ring gearmember 1044, and a planet carrier assembly member 1046. The planetcarrier assembly member 1046 includes a plurality of pinion gears 1047rotatably mounted on a carrier member 1049 and disposed in meshingrelationship with both the sun gear member 1042 and the ring gear member1044.

The planetary gear arrangement 1018 also includes seventorque-transmitting mechanisms 1050, 1052, 1054, 1056, 1057, 1058 and1059. The torque-transmitting mechanisms 1050, 1052, 1054 and 1056 arerotating type torque-transmitting mechanisms, commonly termed clutches.The torque-transmitting mechanisms 1057, 1058 and 1059 arestationary-type torque-transmitting mechanisms, commonly termed brakesor reaction clutches.

The input shaft 17 is continuously connected with the sun gear member1022, and the output shaft 19 is continuously connected with the planetcarrier assembly member 1046. The ring gear member 1024 is continuouslyconnected with the ring gear member 1044 through the interconnectingmember 1070. The sun gear member 1022 is continuously connected with theplanet carrier assembly member 1036 through the interconnecting member1072. The sun gear member 1032 is continuously connected with the sungear member 1042 through the interconnecting member 1074.

The ring gear member 1044 is selectively connectable with the planetcarrier assembly member 1046 through the clutch 1050. The ring gearmember 1024 is selectively connectable with the ring gear member 1034through the clutch 1052. The planet carrier assembly member 1026 isselectively connectable with the ring gear member 1034 through theclutch 1054. The ring gear member 1034 is selectively connectable withthe planet carrier assembly member 1046 through the clutch 1056. Thering gear member 1024 is selectively connectable with the transmissionhousing 1060 through the brake 1057. The planet carrier assembly member1026 is selectively connectable with the transmission housing 1060through the brake 1058. The sun gear member 1032 is selectivelyconnectable with the transmission housing 1060 through the brake 1059.

The truth table shown in FIG. 11 b describes the engagement combinationsand the engagement sequence necessary to provide two reverse driveratios and the eight forward speed ratios (as well as an extra thirdforward speed ratio (3′)). A sample of the numerical values for theratios is also provided in the truth table of FIG. 11 b. These valuesare determined utilizing the ring gear/sun gear tooth ratios also givenin FIG. 11 b. The N_(R1)/S_(R1) value is the tooth ratio for theplanetary gear set 1020; the N_(R2)/S_(R2) value is the tooth ratio forthe planetary gear set 1030; and the N_(R3)/S_(R3) value is the toothratio for the planetary gear set 1040. As can be determined from FIG. 11b, each of the single step forward interchanges is of the singletransition variety. Also given in FIG. 11 b is a chart describing thestep ratios between the adjacent forward speed ratios and the reverse #2to first forward speed ratio.

While the best modes for carrying out the invention have been describedin detail, those familiar with the art to which this invention relateswill recognize various alternative designs and embodiments forpracticing the invention within the scope of the appended claims.

1. A multi-speed transmission comprising: an input shaft; an outputshaft; first, second and third planetary gear sets each having first,second and third members; said input shaft being continuouslyinterconnected with a member of said planetary gear sets, and saidoutput shaft being continuously interconnected with another member ofsaid planetary gear sets; a first interconnecting member continuouslyinterconnecting said first member of said first planetary gear set withsaid first member of said second planetary gear set; a secondinterconnecting member continuously interconnecting said second memberof said first planetary gear set with said first member of said thirdplanetary gear set; a third interconnecting member continuouslyinterconnecting said second member of said second planetary gear setwith said second member of said third planetary gear set; a firsttorque-transmitting mechanism selectively interconnecting a member ofsaid first or second planetary gear set with a stationary member; asecond torque-transmitting mechanism selectively interconnecting amember of said second or third planetary gear set with said stationarymember; a third torque-transmitting mechanism selectivelyinterconnecting a member of said second or third planetary gear set withsaid stationary member; a fourth torque-transmitting mechanismselectively interconnecting a member of said first planetary gear setwith a member of said second or third planetary gear set; a fifthtorque-transmitting mechanism selectively interconnecting a member ofsaid second planetary gear set with a member of said first or thirdplanetary gear set; a sixth torque-transmitting mechanism selectivelyinterconnecting a member of said first, second or third planetary gearset with another member of said first, second or third planetary gearset; a seventh torque-transmitting mechanism selectively interconnectinga member of said first, second or third planetary gear set with anothermember of said first, second or third planetary gear set, or with saidstationary member; said torque-transmitting mechanisms being engaged incombinations of two to establish at least eight forward speed ratios andat least one reverse speed ratio between said input shaft and saidoutput shaft.
 2. The transmission defined in claim 1, wherein saidfirst, second and third torque-transmitting mechanisms comprise brakes,and said fourth, fifth, sixth and seventh torque-transmitting mechanismscomprise clutches.
 3. The transmission defined in claim 1, wherein saidfirst, second, third and seventh torque-transmitting mechanisms comprisebrakes, and said fourth, fifth and sixth torque-transmitting mechanismscomprise clutches.
 4. The transmission defined in claim 1, whereinplanet carrier assembly members of each of said planetary gear sets aresingle-pinion carriers.
 5. The transmission defined in claim 1, whereinat least one planet carrier assembly member of said planetary gear setsis a double-pinion carrier.
 6. A multi-speed transmission comprising: aninput shaft; an output shaft; a planetary gear arrangement having first,second and third planetary gear sets, each planetary gear set havingfirst, second and third members; said input shaft being continuouslyinterconnected with a member of said planetary gear sets, and saidoutput shaft being continuously interconnected with another member ofsaid planetary gear sets; a first interconnecting member continuouslyinterconnecting said first member of said first planetary gear set withsaid first member of said second planetary gear set; a secondinterconnecting member continuously interconnecting said second memberof said first planetary gear set with said first member of said thirdplanetary gear set; a third interconnecting member continuouslyinterconnecting said second member of said second planetary gear setwith said second member of said third planetary gear set; and seventorque-transmitting mechanisms for selectively interconnecting saidmembers of said planetary gear sets with a stationary member or withother members of said planetary gear sets, said seventorque-transmitting mechanisms being engaged in combinations of two toestablish at least eight forward speed ratios and at least one reversespeed ratio between said input shaft and said output shaft.
 7. Thetransmission defined in claim 6, wherein a first of said seventorque-transmitting mechanisms is operable for selectivelyinterconnecting a member of said first or second planetary gear set withsaid stationary member.
 8. The transmission defined in claim 6, whereina second of said seven torque-transmitting mechanisms is operable forselectively interconnecting a member of said second or third planetarygear set with said stationary member.
 9. The transmission defined inclaim 6, wherein a third of said seven torque-transmitting mechanisms isselectively operable for interconnecting a member of said second orthird planetary gear set with said stationary member.
 10. Thetransmission defined in claim 6, wherein a fourth of said seventorque-transmitting mechanisms is selectively operable forinterconnecting a member of said first planetary gear set with a memberof said second or third planetary gear set.
 11. The transmission definedin claim 6, wherein a fifth of said seven torque-transmitting mechanismsis selectively operable for interconnecting a member of said secondplanetary gear set with a member of said first or third planetary gearset.
 12. The transmission defined in claim 6, wherein a sixth of saidseven torque-transmitting mechanisms selectively interconnects a memberof said first, second or third planetary gear set with another member ofsaid first, second or third planetary gear set.
 13. The transmissiondefined in claim 6, wherein a seventh of said seven torque-transmittingmechanisms selectively interconnects a member of said first, second orthird planetary gear set with another member of said first, second orthird planetary gear set or with said stationary member.
 14. Thetransmission defined in claim 6, wherein planet carrier assembly membersof each of said planetary gear sets are single-pinion carriers.
 15. Thetransmission defined in claim 6, wherein at least one planet carrierassembly member of said planetary gear sets is a double-pinion carrier.